The present invention relates to a thin, small relay which is mounted chiefly on printed boards. Especially, the invention relates to an electromagnetic relay of the construction in which an electromagnet, having at least a core, a coil and an armature, is accommodated in a box-like insulated housing which has surrounding walls to hold terminals of fixed and moving contacts, and to a method of manufacturing the same.
FIG. 1 is a perspective view of a conventional small electromagnetic relay (hereinafter simply referred to as a relay), and FIG. 2 is a perspective view illustrating the relay of FIG. 1 in a disassembled manner. In these drawings, reference numeral 10 denotes a support member composed of an insulating material which forms a rectangular box with its upper side being open and the bottom being closed. The opposing side walls 11 of the support member 10 have through holes 12 in which terminals will be inserted. The side walls 11, further, have projections 13 for fastening a moving contact spring member on the upper surfaces thereof, and projections 15 for securing a yoke plate in the recessed portions 14. A side wall 16 has a slit or slot 17.
Reference numerals 20, 20', 21, and 21' denote fixed contact terminals, 22 and 22' denote coil terminals, and 23, 23' denote terminals for lead contacts. These terminals have at their lower ends escape-preventing pieces 24 that fold after the terminals are inserted in the through holes 12 of the side walls 11. The fixed contact terminals 20(21) and 20'(21') have a difference in height at the contact points 25. Moving contact springs, which will be mentioned later, are disposed between the contacts 25 to form transfer contacts.
Reference numeral 30 denotes an electromagnet consisting of a core 32 on which a coil 31 is wound, an L-shaped yoke plate 33, and an L-shaped armature 34. Lead wires of the coil 31 are wound on connection portions 26 of coil terminals 22, 22' and are soldered. The core 32 is fastened by caulking at one end to the yoke plate 33; the other end of the core 32 works as an attracting portion 35 to attract the armature 34. The yoke plate 33 has projections 37 with holes 36 on both sides thereof, and the armature 34 has a drive piece 38 for engaging a moving contact spring member and a projection 39 in the narrow portion thereof. Reference numeral 40 denotes a moving contact spring member having a pair of moving contact springs 41 with one end of each spring 41 being fastened to a molded member 42.
Each of the moving contact springs 41 is slightly bent. One end of each contact spring 41 has contacts 43, 43' on the front and back surfaces to come into contact with the fixed contacts 20(21) and 20'(21'), and the other end has a connection piece 45 that is directly soldered to connection portion 27 of the terminal 23 or 23' for the lead contact. A molded insulator 44 is provided at the central portion of each contact spring 41. The molded member 42 has, on both sides, holes 46 into which the projections 13 are inserted. Reference numeral 50 denotes a release leaf spring which also works to prevent the armature 34 from escaping, and which consists of an L-shaped spring piece 52 having a hole 51 in one end thereof, and insertion pieces 54 with rising portion 53, which are formed as a unitary structure. Reference numeral 60 denotes a transparent relay cover.
How the above-mentioned relay is assembled is described below. In the relay, the individual members are all mounted through the openings of the support member 10. That is, fixed contact terminals 20, 20', 21, 21', coil terminals 22 and 22', and contact lead terminals 23, 23' are inserted in the through holes 12 of the support member 10, and are secured by escape-preventing pieces 24. The electromagnet 30 is disposed in the housing with the core 32 on the lower side and the yoke plate 33 on the side of the opening, whereby projections 37 and holes 36 are fitted into the recessed portions 14 and projections 15. The armature 34 is inserted between one end a of the yoke plate 33 and the side wall 16, with the drive piece 38 disposed on the yoke plate 33, such that one end a is brought into agreement with the folded portion b of the armature 34. Under this condition, the armature 34 faces the attracting portion 35, and the folded portion b is folded at an angle that is slightly greater than 90.degree., so that a gap is formed relative to the attracting portion 35.
The release leaf spring 50 is inserted in the slit 17 and is allowed to stay therein utilizing the resilient force of the rising portion 53. The spring piece 52 of the release leaf spring 50 is positioned on the armature 34, so that the projection 39 is fitted into the hole 51.
In the moving contact spring assembly 40, projections 13 are fitted into the holes 46 to place the molded member 42 on the side walls 11, with the moving contact springs 41 of the moving contact spring assembly 40 being interposed between the fixed contact 20(21) and the fixed contact 20'(21'), and with the insulator 44 being placed on the drive piece 38. Thereafter, projections 13, 15 protruding through holes 36, 46 are heated and caulked so that yoke plate 33 and the moving contact spring assembly 40 become attached to the side walls 11 of the support member 10. At the same time, the lead wires of the coil 31 are wound and soldered onto the connection portions 26, and the connection portions 27 are soldered to the connection pieces 45. Finally, the relay cover 60 is mounted on the support member 10 to produce the relay.
In the above-mentioned relay, the moving contact springs 41 are electrically connected to the fixed contact terminal 20'(21') when the electromagnet is not being excited. When the electromagnet 30 is excited, the armature 34 is attracted to the attracting portion 35, whereby the drive piece 38 pushes the moving contact springs 41 up via the insulator 44; the moving contact springs 41 come into contact with the fixed contact terminals 20(21) to switch the contact.
In the above-mentioned conventional relay, however, the following inconveniences occur, since electromagnet 30, moving contact spring member 40, release leaf spring 50, and contact spring terminals 20, 20', 21, 21' are successively mounted into the box-shaped housing 10 which is formed by molding and which is composed of an insulating resin.
(1) A lot of assembling steps are necessary to manufacture a relay, requiring extended periods of time and a long assembly line.
(2) The assembling operation becomes cumbersome as the assembling operation proceeds. Therefore, parts tend to be deformed, and it becomes difficult to produce relays with a high degree of reliability.
(3) So many parts are assembled in the housing that the above-mentioned defects (1) and (2) become conspicuous, particularly when relays of a small size are constructed. Accordingly, reducing the size of the relay cannot be achieved.